Plastic bottle molding machine



April 23, 1 957 E. R. KNowLEs PLASTIC BOTTLE MOLDING MACHINE .3 Sheets-Sheet 1 Filed April 28, 1952 Pwfa l u F1 .l kwh.. f lllwli WNW/lf lllh QW Nm@ ww. n wm.. 1u ,m \mam/ lull IIN l l l |II\-`I l llnll IIKV I Il "WEL April 23, 1957 E. R. KNowLl-:s

PLASTIC BOTTLE MOLDTNG MACHINE 5 sheets-sheet 2 Filed April 28, 1952 INVENTOR. bn/4R0 KVQW E; BY

April 23, 1957 E. R, KNOWLES 2,789,313

PLASTIC BOTTLE MOLDTNG MACHINE IN V ENTOR.

PLASTIC EQTTLE MOLDING MACHINE Edward R. Knowles, Elizabeth, N. J., assignor to Lapin Products, lne., Newark, N. J., a corporation of New York Application April 28, 1952, Serial No. 284,725

3 Claims. (Cl. 18-5) The present invention relates to a process and method for molding containers of plastic materials, and it particularly relates to a process and method for molding bottles.

Although not restricted thereto, the present invention will be particularly described in its application to a mechanism and machinery for molding plastic exible ited States Patent O bottles of the type having a screw neck connection and a collapsible plastic container or cylindrical portion.

It is among the objects of the present invention to provide a novel process and mechanism for molding bottles and other containers at relatively high production and at low cost by simple injection molding procedures without the need of special manipulations, and all in one operation, together with the neck of the bottle.

Another object is to provide a high rate, low cost, mass production molding procedure for bottles of plastic materials which will eliminate the necessity of cutting olf and utilizing special size blobs of plastic materials which are to be blown into shape and which will also eliminate the necessity of such manipulations as would be required when the bottles are formed from extruded tubing.

A further object is to provide a molding procedure and mechanism for making containers which will eliminate the necessity of separate extrusion of cylindrical or tubular material which must then be subsequently shaped and which will produce the finished bottle and desirable wall thickness and neck size and shape by the cycle of an injection molding machine.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accomplishing the above objects is has been found most satisfactory, according to one embodiment of the present invention, to provide a multi-.cavity mold in which the opposite halves of the cavity or moldv sections will be provided with recesses to receive the molten plastic which may be measured, heated to fluid or liquid condition and then forced into the mold recess under piston pressure.

The mold recess is desirably shaped so as to form the neck of the bottle and a cylindrical tubular extension thereof having a bottom closure.

This is done by forcing the liuid plastic material into a cylindrical recess having a removable core. V The recess is normally formed by a sleeve or shell pin which, after the initial shot of resin has been forced into position, may be withdrawn. This sleeve or shell pin when withdrawn will permit the resin to expand under lluid pressure to the desired bottle or container size. The inside core or pin is desirably provided with means operaytive after the withdrawal of sleeve or shell pin to force uid such as air under pressure inside of the still plastic cylinder of resin which has been forced into the initial cavity.

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This fluid or air under pressure will then expand the container until it has a size and shape of the outside cavity which has been under-covered by removal of the sleeve or shell pin.

In short, the cavity of the mold has an inside removable core and an outside removable shell pin spaced from one another to form an initial tube or cylinder of plastic as a result of injection molding.

This tube is then subsequently expanded to the desired container size after removal of the shell pin or sleeve by a fluid inserted through the inside core or pin.

Then the mold may be opened and the bottles removed, attached to the inside core pin and upon removal of the core pin the bottles are in final nished shape without subsequent blowing or forming operations.

With the foregoing and other objects in view the invention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described, and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views:

Fig. l is a side elevational view of one complete mold partly'in section showing the core pin and sleeve or shell pin both in position ready to receive a shot of plastic material from the plunger of the injection molding machine.

Fig. 2 is a side elevational view of the outside of the closed mold structure upon the line 2-2 of Fig. l.

Fig. 3 is a fragmentary transverse sectional view upon the line 3 3 of Fig. l showing the end of a closed cavity in the mold structure of Figs. 1 and 2.

Fig. 4 is a transverse vertical sectional view upon the line 4-4 of Fig. 2 upon an enlarged scale as compared to Fig. 2. Y

Fig. 5 is the same view as Fig. 4 but with the shell pin removed and with the container enlarged to the shape of the final cavity.

Fig. 6 is a fragmentary transverse sectional View upon the line 6 6 of Fig. 4.

Fig. 7 isa fragmentary transverse horizontal sectional view upon the line 7-7 of Fig. 5 showing the container enlarged to its final shape.

Fig. 8 is a side elevational view showing the iinal container partly in section to show the wall thickness.

In Fig. 8 there is shown a bottle A which is merely a typical shape of container which may be produced at low cost and at maximum production by ythe present invention.

The container A as shown has a cylindrical side wall 10 of slightly increased diameter towardvits base as indicated at 11, with a slightly elevated or indented bottom 12.

The top of the bottle A has a shoulder 13 and a small diameter neck 14 which" may be provided with a screw thread 15.

The bottle A may be section molded of polystyrene, cellulose acetate, polyethylene, nylon, cellulose butyrate, methyl methacrylate and other suitable plastic molding materials.

The entire mold or cavity, as best shown in Fig. 2, is made of two sections, B and C, which are shown as close together along the parting line D as indicated in Figs. l and 2. v

The mold when closed before injection of the liquid plastic material receives the core pin or mandrel E, having a central air valving arrangement F supplied from the air passages G.

It also has a removable shell pin or cylindrical shell or sleeve H. This sleeve H may be manually or automatically withdrawn.

material maybeeini-tia-lly inserted through the feed system K. The recess l' is the spacepbetween the core pinE and -theJshell-*pin Hfwhentheshell-pin'is closed around the core pin, as indicatedf-in'lig.

fReferringYparticularlyYtoFigs. 4 and 5 the mold sections C and B are provided with'the recesses 25' which arezslightly-conical shapeasebestshown in'Figs. 'l and 4. 'These recessesterminateat -26- and 27.

Fitting withinthe-=recess beforethe shot ofrplastic ma- Jterialis the shell-pinH--the end 2S got-which abuts the .end 26 of the recess 25.

VThe shellipinv slides inthe opening 29 in the mold structure B and its end 1-is-provided with an enlargement or shoulder-30 -which.'its 4intherecess 31 inthe drawnfout Vplateibaror--bushing top pad 32. The plate or'bar 32 is mountedI to moveonthe' bushing bottom pad lSi?, by means of thexbolts or screws 34 (see also Fig. l).

-In Fig.-4 the shell pin Hl is shown in its innermost position .while in @Fig 5 it is shown in-its outdrawing position. The movement ofthe shell pin His controlled by means of the plunger rod 35- (seeFig. l) which will con- -trol @thelmovement ofthe pads 32'and 33.

.Referring to the mold structure as shown upon Fig. 2,

lthe topplate -carries a chase 41 which receives the leader pinv42. Thisleader-pin engages the bushing '43. The bottom plate-440i the mold sections C as shown in Fig. Zis attached to the centerplate which in turn is connected to the inside plate '46.

The chase 41`may be dividedin sections along the partingflines 47 and'48fas shown-in Fig. 2.

In themold shown in iFig. l-the-screws 49 and the pin opening 50 are indicated butlthey havenobearing on the invention.

`The back barf51`will1be positioned at the top ofthe mold and will carry the core pins E. The screws '52 will vhold the -plate53 in position.

The -air vconnection Vto the V-air'conduit system G `may be made at the threaded opening 54 while a water connectionmay bemade at the threaded connections 55jleading to the passageways S6. The end chase elements 57 may .be held in `positionby the screws or v,bolts 58.

Dowel pin openings are also provided at 59 and 60 to assure proper alignment. Thecavity inserts 61 and screws -62 are conventional elements yconstituting no part of the present invention.

The lower part of the mold is provided with water conneetions as indicated at 63 and passages v64. The core pin E has a head which iits in the recess 76 in the bar 51. This head is heldin position by the screws or bolts 77.

The head 75 is `provided with an opening 78 which receives the adjustable screw plug 79. The screw plughas a knob which centers ythe coil lspring 81 and adjusts the pressure thereon. The coil spring ts in the recess 82 in the upper-part 83 of the core pin E.

The spring 81 reacts upon the head 84 of the piston 85. The piston 85 has apacking cup 86 held in position by the screw 87. Inside of the cup is the head 88 of the valve rod F. The portion 93 of the core pin E has a peripheral enlargement 89 having the radial passages 90 therein which communicate with the air passageway 91.

The air will pass Afrom the air passageway 91 into the space 92 under the piston `85 and then into the narrow channel or passageway 93 between the core pin E and the inside valve rod F.

The inside valve rod F at its lower end has a plurality of lguide ins 94 which ride on the inside face of the passageway within the core pin E.

The lower end yof therod 'F has aconical'valve -face 95 which is conformed 'to 'tit against the 'valve seat 96 and prevent passage of air through the passageway 93 and our-throughtheesmallropening 97 atthe bottomof the core pin E.

When, however, the valve rod F is lifted, as shown in Fig. 5, the air may then ow out through the small opening 97 into the space outside of the core pin E and inside of the cavity 25.

However, air will only be applied under pressure throughthe'system G and the'passageway 91 when the shellV pin H is fwithdrawn into the position shown in Fig. 5.

The plastic material which is fed into the cavity l when the mold is in the position as shown in Fig. 4 will enter through the sprue or,inlet and through the runner passageway 111 to the ring`gate'112 forming part of the passageway system K.

This plastic material under pressure will enter around the core pin E and will fill in the space 113 forming the neck 15 of the bottle A andwill flow into the opening l vforming the initialtubular form.

In operation, ithe vvmold sections'B and C will first be closedY asshownY in Figs. 'l and 2 with the shell pin H and the core pin E in position as shown in Fig. 4. ln this ypositionthe valve rodFiwill be pressed downwardly by thet'spring' 81 so astoclose its conical face 95 againstthe conical valve=seat"96 closing ol the small passageway 97.

in this positionthe air pressure will be cut off from the inlet G and the passagewayi91 and the plastic material Will bevforced'into the mold under pressure through the -sprue 110,the runner i111 andthe gate 112 into the space at"113 and atJ in Fig. V4.

When' the Huid .plastic material'has filled this space the "shell'pin'l-Iwill be'withdrawn-by operation of the pads 32 and 33 tothe position shown inFig. 5 with its upper kedge128,1however,beingslightly above thebottom of the cavityi ats-indicated `at 27 'in Fig. 5

Thenair'Y pressure will'be applied through thepassage- `way'system G ,and91'wh'ere vit will enter the space 92 `through theopenings'90. 'This jwill cause the piston 85 to be pressed'upwardly compressing the spring as shown in Fig.` 5and'opening'the valve '95 and permitting air to ow'out-throughthetsm'all opening 97. This will expand the plastic tubeiinftheopening J to the final size or shape of thelbottle as indicated at A in Figs. Sand 8.

'Ther-etis shown in Figs. 4 4and 5 'an insert or plug or -plunger'125 Lwhich-is.carriedlbythe member r126 and the 'rod 127. VThis plugvwill normallybe'in top position when the plastic material is originally forced into position in the arrrangementsliownin Fig `\5.

"When, howev'er, the shell pins H are lowered to the :position shown in Fig. 5 the plug 125 will be slightly 'lowered so 'as 'to enablethe bottom V12. to'bcV pressed away "-fromthe'operiing97 and`topermit'llow of air under pressure -to'permit'expans'ion'of the sidewalls of the bottle as indicated nJFg. l5.

lIt 1is thus japparentthatthe applicant has provided an economical high production "injection -mold process for molding 'plastic bottles or containers which may be utilized 'to produce lsuch containers in finished form in one operation.

When ythe ybottleshave"been vexpanded tothe shape as shown in Fig 5,'the'two mold sections B and C may be opened land the "bottles vcarried by the core pins E may be Aremoved and :subsequently 'removed from such core pins.

Another set of Ycore pins .on the bar S1 may be then placed 'in position and 'the molding operation repeated lirst by the astep of Ilo'rrning the small cylindrical element in the recess J inrFig -6 :followed by air pressure expansionlinl'Fig. 5. The l-o'utlet 32a is an air relief outlet from the molding recess.

This process land `rno'lding arrangement permits complete production of the Abottles without handling or inter mediate operations yinvolving extrusion of a tube, cutting of the tube, and then expansion of the tube into 4bottle shape. it is lnot necessary `to handle any particularly weighed blobs of 'plastic 1materials and the recess J will automatically measure olf the right amount of plastic ma- 5 terial without complicated weighing or metering apparatus.

As many changes could be made in the above method and apparatus for molding plastic bottles, and many widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Having now particularly described and ascertained the nature of the invention, and in what manner the same is to be performed, what is claimed is:

l. In a plastic bottle injection molding machine for making a bottle having a relatively narrow neck and cap receiving portion and a relatively wide lower container portion, a two-piece mold forming a cavity which forms the external shape of said bottle, a core pin projecting axially downwardly into said cavity, said core pin having a central axial passageway and an upper portion above said cavity with a peripheral ridged bead having a plu-` rality of radial inlet passageways to said axial passageway to receive air under pressure, an outlet opening at the bottom of said core pin, a reciprocating conical valve at the lower end of said pin passageway to seal said outlet, an elongated valve rod extending through said passageway to said conical valve, reciprocating means to reciprocate said rod and valve, and a withdrawable cylindrical shell pin inserted within said cavity and positioned concentrically around said core pin to form an initial annular recess between the shell pin and core pin, which recess is initially filled with plastic and sai-d shell pin being withdrawn to permit said plastic to be expanded to the shape of the cavity.

2. T he machine of claim l, the upper portion of said core pin having an enlarged pressure chamber communieating with said radial inlet passageways and said axial passageways and receiving said reciprocating means.

3. The molding machine of claim l, in which said reciprocating means consists of a coil spring returned piston which is actuated by the air under pressure passing inwardly through said radial inlet passageways.

References Cited in the file of this patent UNITED STATES PATENTS 2,469,130 Rodman May 3, 1949 

